Study: Irrigation increases ‘extreme weather’

hills of southern San Joaquin County, July 1, 2007 (Photo credit: Michael Patrick)

Readers may recall that Dr. John Christy found that irrigation increases temperatures measured in the central valley. This study finds it also increases rainfall and storms due to the additional available moisture. CO2 is not listed as being part of the equation, which makes the ‘extreme weather’ meme being pushed by alarmists even less likely. – Anthony

UCI study finds that doubling of moisture in air has positive, negative effects

Irvine, Calif., Jan. 28, 2013 – Agricultural irrigation in California’s Central Valley doubles the amount of water vapor pumped into the atmosphere, ratcheting up rainfall and powerful monsoons across the interior Southwest, according to a new study by UC Irvine scientists.

Moisture on the vast farm fields evaporates, is blown over the Sierra Nevada and dumps 15 percent more than average summer rain in numerous other states. Runoff to the Colorado River increases by 28 percent, and the Four Corners region experiences a 56 percent boost in runoff. While the additional water supply can be a good thing, the transport pattern also accelerates the severity of monsoons and other potentially destructive seasonal weather events.

“If we stop irrigating in the Valley, we’ll see a decrease in stream flow in the Colorado River basin,” said climate hydrologist Jay Famiglietti, senior author on the paper, which will be published online Tuesday, Jan. 29, in the journal Geophysical Research Letters. The basin provides water for about 35 million people, including those in Los Angeles, Las Vegas and Phoenix. But the extra water vapor also accelerates normal atmospheric circulation, he said, “firing up” the annual storm cycle and drawing in more water vapor from the Gulf of Mexico as well as the Central Valley.

When the additional waves of moisture bump into developing monsoons, Famiglietti said, “it’s like throwing fuel on a fire.”

Famiglietti, an Earth system science professor in the School of Physical Sciences, and colleague Min-Hui Lo, a postdoctoral researcher at the University of California Center for Hydrologic Modeling who is now at National Taiwan University, painstakingly entered regional irrigation levels into global rainfall and weather models and traced the patterns.

“All percent differences in the paper are the differences between applying irrigation to the Central Valley and not applying it,” Famiglietti said. “That’s the point of the study – and the beauty of using computer models. You can isolate the phenomenon that you wish to explore, in this case, irrigation versus no irrigation.”

Famiglietti’s team plans to increase the scope of the work to track how major human water usage elsewhere in the world affects neighboring areas too. A better understanding of irrigation’s impact on the changing climate and water availability could improve resource management in parched or flooded areas.

About the University of California, Irvine: Founded in 1965, UCI is a top-ranked university dedicated to research, scholarship and community service. Led by Chancellor Michael Drake since 2005, UCI is among the most dynamic campuses in the University of California system, with more than 28,000 undergraduate and graduate students, 1,100 faculty and 9,400 staff. Orange County’s second-largest employer, UCI contributes an annual economic impact of $4.3 billion. For more UCI news, visit news.uci.edu.

Lets see what the paper says but we need to keep things in focus. The landscape of the Valley is a giant erosional feature and the waster that did most of that work is long absent. Having increases in water, here and other SW basins, now quite dry, from what ever source is shall we say not abnormal except the the myopic thinking of those who believe they know that which they do not.

Well they should pump even more water vapor into that area.Lake Mead is low so more run off is a good thing. I can already see it now, government Grants to install giant mist blowers in areas across the USA to control the weather. Weather is the one thing they can not control YET and tax. I would guess the government is paying big $$$ for the studies. They may impose new taxes on the farmers in CA for damages caused by irrigating crops releasing water vapor??

Dear Anthony,
So you are not going to post my comment and information about what conservatives knew and believed about climate change all the way back in 1981? If not, you are proving to be exactly what I feared: a person only interested in sharing information as long as it is the information you want to share. Please reconsider. This is important. I have some top journalists following my blog now, and you should also remain open to addressing all sides if you want to remain credible. http://www.buckyworld.me
REPLY: “top journalists” Wow, how transparent. And you’ve already stated in your diatribes that I’m not credible, so your silly carrot doesn’t work here. But the the answer is still no, because 1. it is off topic (as you have proven here with this comment on a totally unrelated thread). 2. all you want to do is build traffic for your website (proven, since you keep adding your tagline URL), all while calling people “deniers” and refusing to answer questions put to you here. What I am going to do is tag you for extra moderation attention, and if you do have something relevant to say that follows our policy it will be approved, all others automatically go to the bit bucket.

I guess all things are relative. I note that they claim: “If we stop irrigating in the Valley, we’ll see a decrease in stream flow in the Colorado River basin,”

Yet, at least in the southern Valley, virtually all the water comes from the Colorado river Basin (I am unfamiliar with the northern and mid central valley water sources). Given he also claims: “Moisture on the vast farm fields evaporates, is blown over the Sierra Nevada and dumps 15 percent more than average summer rain in numerous other states. Runoff to the Colorado River increases by 28 percent, and the Four Corners region experiences a 56 percent boost in runoff.”

The numbers do not add up. If much of the water, taken from the Colorado, is sent outside its basin, then stopping the taking of water from the Colorado would at least leave more in the basin. Location I can understand. Right now, Mexico gets precious little from the river since California (and other states) drain off most of it before it gets there. So perhaps he is saying that the US would see less, but the net affect to the entire system would seem to be an increase in the stream flow.

In the 1960’s there were 8 million hectares under irrigation. Latest info I could find makes that 280 million hectares. With H2O attributed to 70 to 96 percent of the greenhouse effect you might think this has an effect!!

Interesting study of evaporation from the Central Valley. I hope some day they will get around to studying the effect of evaporation from high level fillings of the Salton Sink, which intermittently created a lake six times the size of the present Salton Sea. There is pretty good evidence for this happening less than a millenium ago. See

“That’s the point of the study – and the beauty of using computer models.” ???
I’m soooo tired of models. Models belong on runways. I’d like to see these people get out from behind their damn desks and make some real world empirical measurements already.

@Juan Slayton – no, the Imperial valley. It is the southern part of the central valley. It is almost all either farmland or desert, and the farmland is irrigated through a series of canals, fed by – the Colorado River.

I thought ‘repurposing’ was a good thing in the great green world in which we live. Repurpose rainfall into stored water. Repurpose the stored water into electricity. Repurpose the used water for irrigation. Repurpose the irrigation water for food and atmospheric water vapor. Repurpose the water vapor into extra rainfall for the deserts of the southwest and great basin.

Where is the ‘gasoline on the fire’ in all of this. If you could take an area with 5″ – 15″ of rain a year and, with additional rainfall, have it become productive for growing more than cholla and sage brush it seems to me that would be a good thing. The word monsoon is used three times in the article, but always in a pejorative sense. Why? Ask the peoples of SE Asia how long they want to go without the monsoon. Or for that matter, anywhere in the world that people depend on regular waves of water for their very existence.

Uncontrolled flooding is not good. But flooding that is captured and stored and repurposed has been the basis of cultural and national growth since the rise of irrigation in ancient Persia. How insipid we have become as a people when we cower in the virtual closets of academia, sucking our collective thumbs and hoping that a celestial mommy will somehow make every challenge disappear so that we can come out and face the defeated bully of monsoon, or water vapor, or (gasp) a 1/2 degree rise in temperature.

I used to ride my motorcycle in the summertime across SE Idaho, which is a combination of desert and irrigated farmland. I didn’t carry a thermometer but one wasn’t needed to detect a significant temperature difference when riding from one type of landscape to the other: The farmland felt a good 5 to 10 degrees cooler than the un-irrigated desert–so much so that we restricted our joyriding to farmland areas.

I’ve long held that irrigation simply supplies water to an inland hydrosphere that would otherwise be wasted by flowing directly into the Snake River and eventually into the Pacific, typically in a couple of early summer months with the spring runoff. That it alters our local climate during the summer is not surprising, but I submit the impact is beneficial by lowering temperatures and making this “desert” a more hospitable place to live. The irrigated crops grown here are also one of the biggest income generators for our state, and attempts at reducing such will be met with fierce resistance by our farmers as well as people who like Idaho potatoes–especially restaurants in the East. Idaho is also the #3 state for milk production, which is a surprise considering the small percentage of this state that is under cultivation.

I’ve also noticed that summer afternoon thunderstorms are common in the mountains to the east and to the north of us (Grand Tetons and Yellowstone, respectively) and while I haven’t used a comparative computer model, I’m sure the frequency and severity of these thunderstorms is increased by local irrigation. I’m happy our farmers are contributing to the local hydrologic cycle. And perhaps states to the east of us appreciate our contribution to their summer rainfall.

Those readers of this blog, who have the time, and don’t live in the SW US ( In which case they probably know this stuff already) might find it amusing to research where the moisture actually comes from that feeds the summer monsoonal flow!

Less and less water is coming from the Colorado River into California. Historically, California used water that was actually claimed by Arizona. It has only been in the past few decades that Arizona has been able to make use of their share of the water.

Most of the irrigation in the San Joaquin Valley comes from reservoirs found in the Sierra Nevada mountains, mostly from Fresno north. There are two giant canals that suck water from the rivers and reservoirs in the north state and pump the water to the south. The Delta-Mendota canal is specifically for irrigation and terminates just west of Fresno. The California Aqueduct transports water from as far north as Oroville dam to areas south and east of Los Angeles.

So the net effect, if this study is in any way accurate, is to take Northern California rainfall and, in a very circuitous manner, deliver more rainfall to the Great Basin and the southwest deserts.

We often get remnants of the summer monsoons that hit Arizona and adjacent states clear up here in Idaho. By the time they reach us, the moisture is pretty much spent, but I’ve seen “monsoon rainfall” in Idaho. (We’re happy to get it whatever the source.)

Re: the topic in hand. I would have thought one would need very large swathes of irrigated land to enable a significant evapo-transpiration effect. I was watching something the other day about the local climate (lake snowfalls?) due to the Great Lakes, and thats all water! I can imagine there are some effects, but given that irrigation has been a human ‘thing’ for many centuries, I don’t think we can call it significant compared to oceanic or natural lake evaporation?

@Anthony – re Ms Ravasio – IIRC, I’m fairly sure that I (and others) said in the very first thread she was posting in, that she was obviously only here to ‘troll’ even after we had welcomed her and tried to be helpful! FWIW – I think you (and us) have been too generous! just my view…

It’s probably a viable first approximation. A more refined analysis would probably show the sum total of irrigated areas throughout the SW are a key causal factor. However the Central Valley is a huge chunk of SW irrigated land.

“All percent differences in the paper are the differences between applying irrigation to the Central Valley and not applying it,” Famiglietti said. “That’s the point of the study – and the beauty of using computer models. You can isolate the phenomenon that you wish to explore, in this case, irrigation versus no irrigation.”

May I suggest those who doesn’t belive in problems caused by irrigation, and for that other causes of erosion due to changes in microtopical biotops without first analysing the ground, to go to the Library. Recommended book Haggett, Peter; Geography a Modern Synthesis, Harper International 1983. Might be a bit old, but it takes care of all questions a scholar or a teacher might need to know in order to analyse and/or teach others!

philjourdan: … the Imperial valley…is irrigated through a series of canals, fed by – the Colorado River.

You are certainly correct here. And the All American Canal gets its cut after the Colorado Aqueduct has already diverted substantial amounts to our coastal cities. But the Imperial Valley is well removed from and has no connection with the San Juaquin (Central) Valley which is the subject of the post.

Actually the Imperial Valley is almost entirely below sea level and was covered with the waters of Lake Cahuilla just a few hundred years ago. Here’s the link again from my comment above:

@JuanSlayton – I read your link. Fascinating. I was aware of the pre-historic lake (as most residents are), but not all the eye witness (many times removed) accounts of it. It is indeed mostly under sea level, as you can ride around and see marks high up on towers with the label “Sea Level”.

My problem was in the nomenclature. I guess technically, the Imperial Valley is the imperial valley and not the “central valley” but the folks down there call it the central valley as well. However, the authors probably were referring to the “official” central valley, so that clears up my confusion.

Believe it or not but there is much water going into the atmosphere in WA, OR, and ID. Once mostly flood-irrigation, there is a great amount of investment in center pivot systems. The former lost water to depths beyond the root zone while the new systems spray water, thus adding directly to atmospheric humidity (evaporation) and indirectly (photosynthesis).
Images:

Coordinates from Google Earth for WA along the Columbia River:
46.3075, -119.0191 Zoom out, slowly; note circles. Near Kennewick.
47.1603, -119.9446 Wine grapes; much land in this area is still rill irrigated.

Just south of these vines is the “Ancient Lakes” area, a result of the Ice Age Floods and a western part of the ‘Channeled Scablands”.

philjourdan says:
January 29, 2013 at 9:40 am
****
Yet, at least in the southern Valley, virtually all the water comes from the Colorado river Basin (I am unfamiliar with the northern and mid central valley water sources). …

This is totally, completely, unequivocally wrong – pure, unadulterated baloney in fact. There is no Colorado River water used in any part of the Great Valley. That would require pumping water from the Colorado, across the Mojave Desert northward and over the Tehachapi Range or Southern Sierra Nevada to be used. That simply doesn’t happen, nor are there any infrastructural systems in place that could make it happen. Water in the Great Valley moves from Northern California southward, running in two majors canals from the Sacramento-San Joaquin Delta along the west side of the San Joaquin Valley until it reaches pumping stations just west of I-5, where it is then shipped south for use in L.A. swimming pools. This one of the major reasons that Northern Californian’s keep hoping that So. Cal. will slide off the state and into the Pacific.

Colorado water IS used in the Imperial Valley, and urban areas along the Southern California coast. I’m not sure, but I believe that the urban use of Colorado water is from Orange southward, or south of Orange. L.A. and points north grab water off the Central Valley and Owen’s Valley projects.

@Duster – You probably should have read the entire comments before posting yours. The issue was resolved as a simple misunderstanding of the nomenclature. The Colorado does indeed irrigate the central valley, just not THE Central Valley. As Juan Slayton pointed out, I was talking about the Imperial valley (the southern part of the California central interior, and a valley), while the authors were talking about the northern stretch.

This appears to be the biotic pump in action.
Generally the biotic pump is associated with forests “pumping” moisture perhaps 1000’s of kilometres inland, or the reverse where deforestation along coastal areas stops that moisture reaching inland thus changing the regional climate. It is thought such effect began to first have a noticeable effect historically when the large scale building of wooden boats began.

Anthony Thank you, just spent 45 minutes reading reference mentioned by buckyworld. Patricia has so missrepresented this report, It was written 2000-2001 and the 1981 climate change reference could only have been global cooling. Thank you for keeping the less than honest off WUWT. chuck

The south west of Western Australia is in a similar situation. Half the Perth water supply is used for irrigation (almost all residential), plus there are 60,000 irrigation wells.

We have nothing like the Sierra Nevada, but if this paper is correct we should see increased rainfall inland and down wind from Perth. We don’t. Rainfall has decreased in these areas over the last 60 years (a period during which Perth roughly tripled in size). But rainfall has increased substantially in the monsoon zone which starts about 500 Kms north east of here.

My interpretation is Perth irrigation has no effect on inland rainfall and the increase in monsoon rains is due to shifts in climatic patterns. I suspect the same is true for the US southwest.

Um, we irrigate during the summer when it doesn’t rain… So that evaporated water just blows away. Are they asserting that it causes a bit more rain in the desert in the summer? (most everything down wind of us is desert. Nevada, Arizona, etc.)

So cooling and making bloom the Great (Central) Valley, and adding a tiny amount of summer water to the deserts of the Western States is somehow bad? I can think of no way at all that it can be anything but spectacularly good. We’re talking places that get less rain in a year than most of the nation gets in a month. Add 20% to that (an outrageous overstatement) and folks would still be in a desert.

So I have no doubt that irrigation puts more water in the air, that must come out as precipitation somewhere. Just not seeing how that will in any way be a problem given California and the Western States being so dry to start with.

Brief Geography Lesson:

California has a Great Valley, often called the Central Valley, that reaches from ‘near’ Oregon down to about 2/3 of the way to Mexico. The State Capital of Sacramento is in the middle of it, about the same latitude as San Francisco. From Sacramento north is named The Sacramento Valley. From Sacramento south is called the San Joaquin Valley. (Each named for the main river down the middle of them). That, together, is one giant drainage basin for the Sierra Nevada mountains to the East, the Cascades to the North and the side of the Tehachapi mountains in the south end that faces north. On the OTHER side of the Tehachapi mountains faces toward the Los Angeles basin. See map here:

The California Aqueduct sucks up enormous quantities of water from the Sacramento Valley and ships it south to the Los Angeles basin Along the way a lot slops out in the deserts of Kern County and related areas in the more southerly parts of the San Joaquin Valley (used to grow things like cotton. A very water intensive crop. In a desert….)

The Imperial Valley is ‘way south’ of Los Angeles. It is basically on the Mexican Border. Colorado River water naturally goes there. In fact, it made the Salton Sea (after a bit of an oppsy with a canal sprung a big leak…)

No Colorado River water goes to the Great (Central) Valley. We export water south…

Anything that causes more water to fall as rain anywhere in the dry Western States is a welcome help.

I lived in west-central Ohio at the time, a little over an hour north of Dayton. We got more snow that Dayton did. The pictures don’t do it justice. I think most were taken after the roads were cleared. Where I was it took a backhoe and a city-type plow 8 hours to make it a quarter mile down a local road.
(Did we have “Global Warming” back then?)

Thinking about how the monsoon process works, I think irrigation does contribute to monsoon rainfall but not directly (primarily) as the authors assume.

Monsoons are driven by near surface heat that drives convection, which in turn pulls in moist tropical air on near continental scales.

Increase atmospheric water vapour and you get an increased greenhouse effect, warmer near surface temperatures and increased convection, and more tropical air drawn in, faster. Which would be the main cause of increased monsoonal rainfall. Although the WV from irrigation would make a contribution.

If these are primarily conclusions based on computer modelling then they are hypothesis and not direct observation. Experience dictates that the conclusions could be as much a product of the assumptions and calculations built into the model as of any real world phenomenon. Confirmation will require real world data.

Ok so for weeks now we have been arguing that there is no statistical increase in “extreme weather” now there is and it’s caused by irrigation – whichissit? I know this is somewhat localised but we can’t have our cake and eat it unless we bake an extra cake labelled “regional (local?) weather phenomenon, in which case this is not about global climate.

This doesn’t make sense: water is well-known moderator of temperatures. Irrigation should result in fewer extremes. What gives?
Oh, groan. Computer models again. Can we PLEASE get back to SCIENCE (experiments and observations) to determine the way things work?

There are towns in Queensland Australia now which are currently under water. Agriculture is a big industry in Queensland. I’m not making the connection — historically flooding is normal in QLD — but imagine the claims that would be made regarding Queensland floods if a study linking CO2 to extreme rain had come out right about now.

It’s a shame you didn’t delay this post until tomorrow when the article comes out. I’d have liked to see their calculation for the amounts of water involved. That is, I’d like to see the comparison between the number of acre-feet used for irrigation and the number of acre-feet that end up coming back down the river. If the ratio was a big number it would make it a lot more believable.

Famiglietti, an Earth system science professor in the School of Physical Sciences, and colleague Min-Hui Lo, a postdoctoral researcher at the University of California Center for Hydrologic Modeling who is now at National Taiwan University, painstakingly entered regional irrigation levels into global rainfall and weather models and traced the patterns.

No mention whether the models have been validated. In which case, the patterns will be whatever they want it to be, right?

Oh, crap! The Sun rose again today. We’ve conducted a study and found both land surfaces and bodies of water warm when the Sun shines on them. It’s certainly worse than we thought. And dear God! Moisture may lead to rain. Since when does a desert need rain? Furthermore, those crops, yes, those plants growing everywhere people live…. Well, more food will just encourage more people to live and have families. And you know what those creatures do. Well, they CHANGE things. They just can’t leave things alone. Always trying to make things better. Well, we should just make sure everything stays the SAME. We must pretend the trees don’t actually grow in the forest, and more trees per acre has nothing to do with less wildlife and more fires. It’s just nature resetting the balance. Right? Is that grey matter coming out of my ears?

On a hot night, step out into a lawned backyard and then move into a cement or paved backyard. The difference is very noticeable. Years ago in Aus when you were allowed to use a firearm and cut a tree down the common means of keeping your house cool was verandahs and lawn surrrounding the house. No AC in those days. Of course it wasn’t as hot either, so some informed people attempt to tell us!!!

@Patricia Ravasio: I went to your buckyworld link. Are you serious? In 1981, people were just beginning to realize that the idea of the world heading into an ice age was anything more than a natural weather cycle. The IPCC was founded in 1988 and a good many of us skeptics, include I, believed in the hypothesis of global warming in the mid 1990’s. That is, until I (and probably many others) thought about it, and delved into the evidence.

Your writing is sophomoric and you’re a bit late to the CAGW party. So your blog site is a loser, and you sound like a whiny flunky. I cannot imagine anyone with sense would use your blog site for anything meaningful. Had I been a believer in CAGW, I would not want you on my side.

The good news is that your blog helps show just how underwhelming the case for CAGW is.

@moderator: I am trying to post a response to @Patricia Ravasio: but I cannot get the page to actually post and let me subscribe to this page. I tried twice and the site shows that I am trying a duplicate post…

[REPLY . . sorry but I can see no issues this end. Perhaps wait a few minutes and try again . . mod]

Up until about 150 years ago, rain and snow fell in the Sierras, and flowed down the hill into the San Joaquin Valley. It was a lush, fertile place. Wildlife and plants were abundant – it was, according to literature, an incredibly beautiful place. There was so much water, in fact, that there were lakes in the valley. Tulare Lake wasn’t drained until the mid-20th century. Near Bakersfield, there is a hill (Shark Tooth Hill) where marine fossils can be found. Lots of water.

In the early 20th century, dams were built to hold back the water so the valley wouldn’t flood all the time, and would allow the farmers to get the water they needed for crops by using irrigation canals.

So, now, we have just ‘delayed’ the water from coming to where it always came – down the hill into the valley. How in the Sam Hill can that cause more extreme weather, when the water that was always there is still there, just in a different way? It’s not like we’ve taken a dry, arid place where there is no water to begin with, and replaced it with a moist environment. The water was, and is, always there.